In a background art, there is conceived a portable electronic apparatus having a wireless communication function and having a mode as a wristwatch. There is such a portable electronic apparatus including a wristwatch main body, a strap for mounting the wristwatch main body to the wrist, and a helical antenna arranged at the wristwatch main body. The portable electronic apparatus is constituted such that an axial direction of the helical antenna becomes orthogonal to the wrist in order to deal with a deterioration in an antenna gain when mounted to the wrist (refer to, for example, Patent Reference 1).
Further, there is conceived a portable electronic apparatus of a background art including an electronic circuit, a display portion, and an antenna arranged at a side of the display portion, wherein the electronic circuit is surrounded by a cabinet for electromagnetic shielding. According to the portable electronic apparatus, the antenna is arranged on an outer side (on a side) of the cabinet for electromagnetic shielding (refer to, for example, Patent Reference 2).
Further, there is conceived a portable electronic apparatus of a background art arranged with an antenna in a shape of C type ring on an outer side of a wristwatch main body, wherein the antenna and a circuit at inside of the wristwatch main body are electrically connected by a feed pin (refer to, for example, Patent Reference 3).    Patent Reference 1: JP-A-11-177328    Patent Reference 2: JP-A-2000-138607    Patent Reference 3: JP-A-2000-59241